This invention relates to air flow duct connectors as for use on clothes dryers and the like.
Air flow duct systems for venting exhaust air from clothes dryers must adapt to a variety of physical positions between the dryer air outlet and the opening in the adjacent wall. This is because each installation typically encounters a different lateral spacing between the outlet on the dryer and the opening in the wall. One duct component which is used to accommodate certain of these dimensional relationships is a telescopically expandable and contractible, two-piece sheet metal rectangular tube assembly with side openings, sometimes called a "periscope" connector because of its visual resemblance to an actual optical periscope. This type of connector is formed of two tubes which are telescopically interfitted, each having a lateral orifice and a lateral sleeve around the orifice. There is a significant limit in the amount of contraction possible with these known commercial connectors because one of the sleeves abuts the end of the other tube. Typically the smallest spacing achievable is six inches, center to center of the sleeves and orifices, but this length does not allow for any telescopic adjustment without making the connection wobbly. Thus, if the dryer outlet is displaced laterally less than this amount, a periscope connector cannot normally be employed. If a longer connector is supplied but the distance to be met is shorter, one of the telescopic tubes must be cut shorter, but cutting a metal tube can be difficult and therefore is usually not done. The installer will be tempted to substitute a piece of flexible plastic duct, but this increases the risk of fire. The minimum spacing between the air flow openings in a conventional connector is actually a function of the maximum spacing of the openings. Presently, assuming a two inch minimum overlap for proper strength of the telescopic connector, to accommodate the widest variations of 61/4" to 22" spacing of the dryer outlet to the wall outlet, it is necessary to have several telescopic connector lengths available, e.g., 61/4" to 61/2", 61/2" to 7", 8" to 10", 10" to 14", and 14" to 22". Therefore, connecting the dryer to the outlet with a proper metal connector meeting fire safety standards and of a proper length can present a significant problem and usually requires availability of several connectors of different lengths. This is not currently available due to the cost and impracticality of so many connectors.
A typical type of telescopic connector is shown in Des. 218,825 to Blumer. Use of such a typical telescopic connector on a gas range is shown in U.S. Pat. No. 2,044,761 to Becvar.
What is needed in the trade is a telescopic air flow duct connector capable of having its inlet and outlet openings variably movable from a significantly wide spacing down to a relatively small spacing so as to accommodate incremental spacing between these two extremes. Moreover, at all of these positions there must not be any significant dead air space adjacent the openings, or lint will collect there and present a potential fire hazard.